Marfan syndrome is an autosomal dominant condition caused by mutations in the FBN1 gene, which encodes fibrillin-1, an important component of connective tissue. It produces features resulting from abnormal connective tissue.
Features
The key features of Marfan syndrome include:
- Tall stature and long neck
- Increased arm span to height ratio
- Arachnodactyly (long, slim fingers)
- High arch palate
- Joint hypermobility, particularly in childhood
- Pectus carinatum (outwardly protruding chest) or pectus excavatum (sunken chest)
Arachnodactyly is a key feature of Marfan syndrome. It refers to abnormally long fingers. Arachno- refers to spiders, and -dactyly refers to fingers. There are two tests for arachnodactyly:
- Steinberg thumb sign: Cross the thumb across the palm to see if it goes past the ulnar border of the hand
- Walker-Murdoch wrist sign: Wrap the thumb and little finger around the opposite wrist to see if the tips overlap
TOM TIP: If a patient in your OSCE appears tall, has long limbs, or has a murmur suggestive of aortic regurgitation, consider Marfan syndrome. Look for other features, such as a high-arch palate, check the arm span, assess for arachnodactyly, and test for hypermobility.
Associated Conditions
- Lens dislocation in the eye
- Joint instability and dislocations
- Scoliosis of the spine
- Spontaneous pneumothorax
- Aortic root dilatation and valve regurgitation
- Ascending aortic aneurysms, with a risk of dissection or rupture
- Mitral valve prolapse (with regurgitation)
Management
Cardiac complications, such as aortic root dilatation and dissection, are the key risk in Marfan syndrome.
Management focuses on reducing cardiovascular stress and the risk of aortic dilatation and dissection. This includes:
- Lifestyle modification (e.g., avoiding high-intensity exercise or heavy weight lifting)
- Medications (e.g., beta blockers and angiotensin II receptor antagonists)
- Careful consideration of pregnancy due to increased risk
Supportive care includes:
- Physiotherapy for joint stability
- Genetic counselling
- Regular echocardiograms
- Regular ophthalmology review
Last updated December 2025
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